VMWare CPU/Mem Total Capacity ESX vs ESXi

[chaddy]

Hi all,

We've been playing with ESXi for a year or so and are finally

implementing some real production servers. We purchased 2 HP DL370 G6

servers with 2x Intel quad cores @ 2.4Ghz and 24GB of RAM and VMWare

Essentials.

So I initially installed ESX on both servers and have been doing some

burn in testing and backup/replication testing. Anyways, we don't make

use of any of the ESX service console so I figured it may worth a try

installing ESXi on one of the servers and see how much additional RAM we

get and how well it runs. So anyway, after the install of ESXi my

memory available capacity grew from 20837MB to 21087MB, but CPU total

capacity dropped from 18712MHz to 16553MHz. And while available memory

grew the total memory capacity dropped from 21825MB to 21087MB. What

could explain this? These are both the exact same servers with the

exact same specs, one is just ESX and the other is ESXi. I know it

likely won't make much of any difference in performance, but it just

irks me a bit. Any input would be great!

Thanks,

-Chad

[Rumple]

the biggest difference is probably the amount of CPU reservatino and memory reservation differences between them,

Take a look at the memory and processor configurations and see if they are configured differently (which they probably are).

[chaddy]

Neither have any CPU reserved and the ESX box has 1237.45 MB of reserved RAM. But even if there are reservations that shouldn't change the Total Capacity, only the Available Capacity I'd think...

-Chad

[RParker]

Well try it on the SAME server, you must have done something different in the BIOS, or perhaps there is a problem with the DIMM. Both ESX versions are EXACTLY the same. The only difference is console or no console.

[chaddy]

I just rebuilt the ESXi server to ESX and I now I see the same amount of CPU and RAM as the other ESX server. So the same server ESXi shows less total capacity for CPU and RAM than when ESX is loaded on it...

-Chad

[geddam]

I would not subscribe to "comparison of ESX and ESXi", However in a

testing environment...these are my comments...

This model comes with 18DIMM slots with Xeon 55xx Nehalem series. Installing ESXi or ESX will make some difference on this model and both are supported platforms.

Example 18 DIMM slot Nehalem configuration:

ed	Max Mem Speed	Bank 1 in Channel Populated	Bank 2 in Channel Populated	Bank 3 in Channel Populated
X5570 (2.93 GHZ)	1333 MHz	1333 MHz	1066 MHz *	800 MHz
X5560 (2.80 GHZ)	1333 MHz	1333 MHz	1066 MHz *	800 MHz
X5550 (2.66 GHZ)	1333 MHz	1333 MHz	1066 MHz *	800 MHz
E5540 (2.53 GHZ)	1066 MHz	1066 MHz	1066 MHz	800 MHz
E5530 (2.40 GHZ)	1066 MHz	1066 MHz	1066 MHz	800 MHz
E5520 (2.26 GHZ)	1066 MHz	1066 MHz	1066 MHz	800 MHz
E5506 (2.13 GHZ)	800 MHz	800 MHz	800 MHz	800 MHz
E5504 (2.00 GHZ)	800 MHz	800 MHz	800 MHz	800 MHz
E5502 (1.66 GHZ)	800 MHz	800 MHz	800 MHz	800 MHz

• The current Xeon 5500 family is a two-socket configuration.

• Memory will run at 1333 MHz, 1066 MHz, and 800 MHz.

• Memory is currently produced in single, dual, and quad rank
  configurations. Dual rank is faster than single rank, quad rank is
  currently limited to 1066 MHz speed.

• Each CPU socket has 3 memory channels for a total of 6 channels per
  server.

• Each channel can accept up to 3 DIMMS. This is why
  the servers currently are made with either 12 sockets (2 DIMMS per
  channel x 3 channels per processor x 2 processor sockets) or 18 sockets
  (3 DIMMS per channel x 3 Channels per processor x 2 processor sockets).

• The maximum memory speed is limited by processor. For example, the
  X5570 has a max memory speed of 1333 MHz, the E5540 has a max memory
  speed of 1066 MHz, etc.

• As more memory is added to a channel, the memory
  will slow down.

• Better performance is achieved when the memory is “balanced” (the
  total amount of memory across channels is the same).

Bottom line, You might see a mild difference between memory usage on these models with ESX and ESXi.

Again you may see a change in behavior after considerable amount of CPU cycles are executed.

Thanks

Ramesh. Geddam,

VCP 3&4, MCTS(Hyper-V), SNIA SCP.

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